The present invention pertains to an improved valve and more particularly pertains to a wear-resistant valve particularly well adapted to the valving of dry solid particulate materials having high flowing densities such as, for example, fluidized solids such as the fluidized catalysts flowed through dense-phase standpipes utilized in fluid catalytic cracking units. The valve of the invention is also well suited to the valving of slurries of coal or other abrasive particulate solids. Because of the abrasive nature of such particulate materials and the fact that such valves are often required in high temperature, high pressure-drop services, wear of the component parts of the valve is a severe problem requiring frequent replacement or repair. Such wear can be particularly severe if the valve is so small that it is not feasible to apply abrasion-resistant surfaces at key wear points.
The prior art discloses valve structures specifically designed for handling fluidized or other solid particulates and shows an awareness of the problems of wear of the component parts of such valves.
Worley et al U.S. pat. No. 4,253,487 discloses a slide valve for use in throttling solids flow comprising a pair of opposed discs that are mounted to slide within a valve body and which are retained by guide bars such that the discs' movement is limited to a back and forth movement. It further discloses (col. 7) that the desired erosion protection of the valve internals is achieved by providing hard-surfacing material such as Stellite, a wear-resistant alloy. The configuration of the disclosed valve is given in detail at lines 30-65 of col. 4.
Efferson U.S. Pat. No. 4,372,338 describes in col. 1 the use of pressure equalization and purge lines in the design of the plug valve to keep the valve free of fine solids thereby reducing its wear. This patent shows a rotary plug valve having pockets 27 which rotate to transport slurry from a low pressure to a high pressure line by indexing the pockets alternately with low and high pressure openings.
Bhide U.S. Pat. No. 4,292,992 discloses a slide gate valve having an inflatable seal element and shows the use of a purge gas arrangement to blast solid particles from the gate surfaces where these make contact with the inflatable seal.
Usnick et al U.S. Pat. No. 4,174,728 discloses a gate valve in which the sealing surfaces of the slidable gate are shielded by the valve seats, and an inflowing purge gas is utilized to sweep the gate clear of particles.
Bailey U.S. Pat. No. 4,009,727 discloses a knife-gate type valve including a cylindrical shaped valve liner which is replaceable and preferably is made of a material such as polyurethane.
Worley et al U.S. Pat. No. 3,701,359 discloses a slide valve which is internally insulated to maintain a lower temperature at the metal body of the valve.
Hoopes U.S. Pat. No. 2,631,759 discloses a slide valve having perforations formed on the inner surfaces of the components of the valve to admit a cushion of air or gas therein to reduce erosion of the valve by solid particulates.
French Pat. No. 2388/183 (ABG-Semca) discloses a valve having a valve head mounted on a C-shaped bar which is affixed to a crankshaft which causes the C-shaped bar to rotate the valve head between open and closed positions.